Adhesive



Patented Dec. 11, 1934 UNITED s'rarss 1,983,650 ADHESIVE Herbert J. Wolfe, Castleton on: Hudson, N. Y., assignor to Fort Orange Paper Company, Castleton on Hudson, N. Y., acorporation of New York No Drawing. Application July 25, 1932, Serial No. 624,649

3 Claims.

My invention relates to adhesives and particularly to a composition of this character which is suitable for securing or gluing together portions of cartons or the like, the surfaces of which are more or less covered with printing ink, paraffine or other like greasy or waxy substances which prevent the employment of ordinary glues.

In the manufacture of boxboard or paper cartons, it is frequently desirable that printing ink for decorative or utilitarian purposes be employed upon the surfaces thereof, or that the material itself be coated or impregnated with some Waterproofing substance. Where the waterproofing composition or the printing ink contains such materials as linseed oil, lithographic varnish, tung oil, perilla oil, hemp oil, synthetic and natural gums and resins, saponifiable waxes, pigments either mineral, organic or manufactured, cobalt, lead or manganese driers, lanolin, wool grease, petrolatum, parafiine Wax, and the like, ordinary glues are useless in securing such printed or Waterproofed surfaces together. For this reason, it has been practically impossible to manufacture glued waterproof cartons of boxboard or paper, employing any of the above materials as a coating for this purpose.

Attempts have been made to solve the problem by incorporating in the adhesive such materials as acetic acid, acetone, alcohol, furfural, carbon tetrachloride, etc. all of which were designed to penetrate the ink film and permit the adhesive to adhere to the underlying board or paper. None of these materials produces a composition which can be successfully used because of the fact that the adhesive penetrates into the absorptive back of the board almost as soon as it is applied, leaving none to attack and grip the coating.

I have discovered that a very effective glue for this purpose can be made by combining a saponifying alkali with an adhesive substance which is not substantially saponified when so combined. The alkali penetrates and saponifies the ink or waterproofing and this permits the adhesive to grip the material of the carton.

The alkali which I prefer to use is caustic potassium because it gives the best results, but it is to be understood that any other saponifying alkali, such for example as caustic sodium, caustic barium, caustic lithium, caustic caesium orcaustic rubidium will function in like manner, and for this purpose are substantially equivalents of caustic potassium. Because of the cost of caesium, rubidium and lithium, and because of the fact that caustic barium is not as soluble in water as caustic soda or caustic potash, it seems probable that commercial applications of my glue will employ either one or both of these last mentioned alkalies.

As pointed out above, it is essential that the adhesive substance employed with the alkali be one that is not destroyed thereby. Animal glues, I find, are immediately saponified and rendered useless as adhesives. On the other hand, the vegetable gums, such as gum-arabic, gum-senegal, gum-tragacanth and gum-lac (shellac) are either not saponified to any degree or, if saponified, nevertheless produce a very sticky glue. Likewise dextrinized starch may be successfully used although the glue is very dark in color and its adhesiveness is appreciably less than the gums mentioned.

The very best results are obtained by using caustic potash.

For the ordinary requirements of the box making industry, an adhesive comprising about Parts by weight Water '75 Potash 34 Powdered gum arabic 40 will be very satisfactory, but it is to be understood that the proportions of the caustic and the gum may be considerably varied without any very material disadvantage. That is to say, the caustic may vary from about 14 parts to about 45 parts by weight while the gum may vary from about 15 parts to about 60 parts by weight of the composition. This represents about the maximum, permissible range of variation. Where the proportion of gum or its equivalent is less than the minimum stated above the adhesiveness of the glue is seriously impaired, and when the proportion of alkali is less than the minimum stated above, the adhesive will not saponify a film of dried ink.

The caustic potash and the gum-arabic or any of the equivalents above mentioned of these substances, may be mixed in the desired proportions in the dry form and dissolved in Water before use to produce an adhesive of the desired consistency. When desired, the glue may be made by first dissolving the caustic in water and then slowly adding the gum or starch and stirring until it is dissolved. The quantity of water employed is, of course, substantially immaterial, and merely affects the viscosity of the adhesive.

While my invention has been developed in and is particularly useful in the art of making paper or boxboard cartons, it is to be understood that it will be found useful wherever it is desired to glue together two surfaces either one or both of which is'covered or partially covered with printers ink or, where the material to be glued has been coated or treated with a greasy or waxy substance which prevents ordinary glues from ad hering.

WhatI claim is: n

1. An adhesive containing, as a saponifying agent, from about 14 to about 45 parts by weight of caustic alkali selected from the group: sodium, potassium, barium, lithium,

' caesium and rubidium, and, as an adhesive agent,

from about 15 to about 60 parts by weight of a substance selected from the group: dextrinized starch, gum-arabic, gum-senegal, gum tragacanth and shellac.

2. An adhesive containing from about 14 to about 45 parts by weight of caustic potash, as a saponifier, and from about 15 to about 60 parts by weight of gum-arabic.

3. An adhesive containing from about 14 to about 45 parts by weight of caustic potash, as a saponifier, and from about 15 to about 60 parts by weight of a substance selected from the group, dextrinized starch, gum-arabic, gum-Senegal, gum-tragacanth and shellac,

HERBERT J. WOLFE. 

